Printing apparatus capable of adjusting ink temperature

Abstract

A printing apparatus is capable of printing images by ejecting ink droplets from nozzles. The printing apparatus includes: a drive signal generation unit which generates ejectable drive pulses for ejecting ink droplets based on image data indicating the number of ink droplets for each pixel, and outputs the ejectable drive pulses to the nozzles; and a temperature measuring unit which measures the temperature of the ink. The drive signal generation unit also outputs non-ejectable drive pulses to the nozzle when the ink temperature is lower than a predetermined temperature. The non-ejectable drive pulses are generated and output in order that even when the nozzle is driven by the non-ejectable drive pulses, no ink droplet is ejected. It is therefore possible to provide, without substantially increasing the production cost, the printing apparatus which can elevate the ink temperature irrespective of the print coverage when the ink temperature is low.

1 . A printing apparatus capable of printing images by ejecting droplets of ink from an ink ejection mechanism, comprising:
 a drive signal generation unit operable to generate ejectable drive pulses for ejecting droplets of the ink on the basis of image data indicative of the number of ink droplets to be ejected for each pixel, and output the ejectable drive pulses to the ink ejection mechanism; and   a temperature measuring unit operable to measure the temperature of the ink,   wherein the drive signal generation unit generates and outputs, in addition to the ejectable drive pulses for ejecting droplets of the ink, non-ejectable drive pulses to the ink ejection mechanism when the temperature of the ink is lower than a predetermined reference temperature, and   wherein the non-ejectable drive pulses are generated and output in order that even when the ink ejection mechanism is driven by the non-ejectable drive pulses, no droplet of the ink is ejected.   
   
   
       2 . The printing apparatus as claimed in  claim 1  wherein
 the drive signal generation unit outputs the non-ejectable drive pulses in time slots in which no ejectable drive pulse is output.   
   
   
       3 . The printing apparatus as claimed in  claim 1  wherein
 the ejectable drive pulses are generated as combination of positive and negative voltage pulses, and the non-ejectable drive pulses are generated as either positive or negative voltage pulses.   
   
   
       4 . The printing apparatus as claimed in  claim 1  further comprising a heater operable to heat the ink,
 wherein the heater halts heating the ink when the non-ejectable drive pulses are output to the ink ejection mechanism.   
   
   
       5 . The printing apparatus as claimed in  claim 1  wherein
 the ink ejection mechanism is capable of ejecting a plurality of color inks, and wherein   the drive signal generation unit determines whether or not to generate the non-ejectable drive pulses independently for each color ink.   
   
   
       6 . The printing apparatus as claimed in  claim 1  further comprising an ink circulation route around which the ink to be supplied to the ink ejection mechanism is circulated.